Polypectomes for surgically removing colonic polyps usually comprise an electrocautery snare retractable into a long flexible sheath by means of an electrically conducting cable and a handle connected to the sheath and operating cable for retracting and protracting the snare and for connection to a source of electric power.
In use, the polypectome with the snare retracted is positioned near a polyp with the aid of an endoscope. Once the polyp is located, the operator employes the handle to protract the snare to its open position. The snare, however, rarely protracts from the sheath ideally positioned to engage the polyp; the operator must manipulate the entire handle in order to rotate the snare. Since the handle has an electrical connection, it is not uncommon for the connection to become entangled around the operator's hand and impede the procedure. Such a snare is shown in U.S. Pat. No. 3,828,790.
This drawback can be obviated by providing a snare which is rotatable while the handle is held stationary in the operator's hand. A surgical snare having an operating cable rotatable in a sheath by means of a rotating assembly mounted above a snare handle is shown in U.S. Pat. No. 3,955,578. While the handle-mounted rotating assembly overcomes a problem of the need to manipulate the entire instrument in order to position the snare, its location away from the main axis of the handle makes it difficult to hold the handle stationary while rotation is effected The problem associated with a rotating assembly mounted away from the longitudinal axis of the handle are increased for operators with small hands.
In both U.S. Pat. No. 3,838,790 and 3,995,578 the operating cable is attached to the handle by external clamping means, such as a clamping knob threaded onto the handle or a set screw threaded into the handle. Knobs and set screws not convenient, are sometimes difficult to use or loosen in use, and are easily lost during the assembly and disassembly of the instrument necessary for cleaning or to replace damaged or bent snares.